ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian dia... more ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian diatomite is introduced. The optimum conditions for removal of heavy metals using Egyptian diatomite ore were studied as primary step for treatment of hazardous materials in water and wastewater. Metal removal as well as phenol was investigated using synthetic solutions at initial concentrations of 50 mg/L of individual metals (Cd, Cu, Pb, Zn and Ni) and 10 mg/L for phenol at constant temperature (25±0.1 °C) and (pH 5.5±0.2). The removal efficiency was determined at different contact time, different pH and different diatomite doses in order to continue with isothermal models as next step. The optimum contact time was varied between metals and phenols. Moreover, it was varied between the studied metals since, contact time for uptake of Cd and Zn was 15 min, for Cu 30 min. and 60 min for Ni and Pb. On the other hand, optimum contact time for phenol removal was more than 60 minutes. The optimum dose for removal of all metals recorded to be 0.9 g. Locally Egyptian diatomite was efficient in heavy metal as well as phenol removal at optimum conditions. According to the optimum conditions study, the selectivity sequence can be given as Pb2+ > Cu2+ > Cd2+ > Zn2+ >Ni2+. The combination between phenol and metals as well as the competition between them is understudy. The aim of the understudied investigations is increasing the efficiency of diatomite by further modification as well as study of adsorption and desorption behaviors with respect to the studied metals, phenols and some other recalcitrant hazardous organic compound
ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian dia... more ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian diatomite is introduced. The optimum conditions for removal of heavy metals using Egyptian diatomite ore were studied as primary step for treatment of hazardous materials in water and wastewater. Metal removal as well as phenol was investigated using synthetic solutions at initial concentrations of 50 mg/L of individual metals (Cd, Cu, Pb, Zn and Ni) and 10 mg/L for phenol at constant temperature (25±0.1 °C) and (pH 5.5±0.2). The removal efficiency was determined at different contact time, different pH and different diatomite doses in order to continue with isothermal models as next step. The optimum contact time was varied between metals and phenols. Moreover, it was varied between the studied metals since, contact time for uptake of Cd and Zn was 15 min, for Cu 30 min. and 60 min for Ni and Pb. On the other hand, optimum contact time for phenol removal was more than 60 minutes. The optimum dose for removal of all metals recorded to be 0.9 g. Locally Egyptian diatomite was efficient in heavy metal as well as phenol removal at optimum conditions. According to the optimum conditions study, the selectivity sequence can be given as Pb2+ > Cu2+ > Cd2+ > Zn2+ >Ni2+. The combination between phenol and metals as well as the competition between them is understudy. The aim of the understudied investigations is increasing the efficiency of diatomite by further modification as well as study of adsorption and desorption behaviors with respect to the studied metals, phenols and some other recalcitrant hazardous organic compound
ABSTRACT Hydrophilic property of Ferroplasma acidiphilum strain was investigated through direct c... more ABSTRACT Hydrophilic property of Ferroplasma acidiphilum strain was investigated through direct contact angle measurements, interaction with hydrocarbons and with the determination of its surface energy components. The contact angles of three different liquids drops (water, chloroform, and 1-bromonaphthalene) positioned on the bacterial lawn were measured. Hamaker constant, electron donor and electron acceptor parameters were calculated. The results of contact angles and those of the interaction with organic solvents showed that the microbe has hydrophilic property. The value of interaction energy, ΔGbwb, between two microbial cells (b) immersed in water (w) was found to be +29.53 mJ/m2 confirming the hydrophilic nature of the microbial cells. The floatability of pyrite under xanthate conditions with and without the microbial cells was examined. The results showed that, when the mineral sample was treated with the microbial cells, the cells rendered their own hydrophilic nature to the mineral surface and the floatability of the mineral decreased dramatically over all pH regions
ABSTRACT Recycled waste glass (RWG), from municipal solid wastes (MSW) sorting operations, may be... more ABSTRACT Recycled waste glass (RWG), from municipal solid wastes (MSW) sorting operations, may be used as a sorbent for cadmium, copper and lead ions removal from industrial wastewaters. To the purpose, the ability of RWG to adsorb Cd2+, Cu2+ and Pb2+ from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount and metal ion concentration. Batch adsorption kinetic experiments revealed that the sorption of Cd2+, Cu2+ and Pb2+ on RWG was very fast and the equilibrium was practically reached after only 60 min at constant temperature and pH (5.6 ± 0.1). It was found that the adsorption mechanisms follow pseudo-second-order kinetics. The adsorption isotherm studies indicate that the adsorption of Cd2+, Cu2+ onto RWG follows Langmuir isotherms, while Pb2+ can follow Langmuir and Freundlich models. The maximum adsorption capacity (q max) for Cd2+, Cu2+ and Pb2+ were 6.29, 6.68 and 11.68 mg/g, respectively. From Dubinin–Kaganer–Radushkevich (DKR), the free energy E-value for Cd2+, Cu2+ and Pb2+ is 14.067, 18.467 and 19.724 kJ/mol, respectively. The positive values of E indicate that the sorption process is endothermic and the energy values for the studied metals sorption on RWG indicate that the sorption process is physisorption.
ABSTRACT Application of microorganisms as surface modifiers in flocculation has generated a great... more ABSTRACT Application of microorganisms as surface modifiers in flocculation has generated a great deal of interest in recent times. The surface properties such as zeta-potential and hydrophobicity of minerals and microorganisms play a major role in determining the adsorption of microorganisms onto the minerals and hence the efficiency of flocculation. The utility of microorganisms, including Escherichia coli (wild-type and genetically modified strain Sip), Arthrobacter nicotianae, Bacillus licheniformis, and Pseudomonas maltophilia, has been evaluated by measuring their zeta-potentials and carrying out adsorption and flocculation experiments. Of the tested microorganisms, adsorption of E. coli strain Sip significantly modified the quartz surface. The zeta-potential of the quartz became highly positive at acidic pH, and its IEP (isoelectric point) was shifted from pH
Journal of colloid and interface science, Jan 1, 2010
The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated expe... more The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically. F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe–mineral adhesion was assessed by the extended DLVO theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61° and this decreased to 36° after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.Effect of cell shape on mineral–microbe interaction energy and adhesion behavior (at pH 10.5).
Zeta potential measurements of silica-induced protein (SIP) Escherichia coli and quartz showed th... more Zeta potential measurements of silica-induced protein (SIP) Escherichia coli and quartz showed that the former are positively charged under acidic condition and negatively charged under neutral and alkaline conditions, with an isoelectric point (IEP) at pH 4.5, while the quartz was always negatively charged. Adsorption experiments with bacteria cells on quartz were conducted under different conditions. The results show that at pH values lower than the IEP of the cells, more cells were adsorbed due to electrostatic forces. However, at pH > 4.5, the amount of adsorbed cells decreased as a result of electrostatic repulsion forces. Zeta potentials of quartz showed that at pH 2.5 a significant change in the surface chemistry of quartz occurred after bacterial treatment. The degree of this change was related to the initial SIP E. coli concentration; at 5 × 107 cells/ml the average zeta potential of biotreated quartz shifted from –30 mV to 0 mV and at higher concentrations the zeta potential shifted to the positive direction and reached a similar value to that of the bacterial cells. SIP E. coli showed hydrophobic properties at pH lower than the IEP, with approximately 60% of the cells moving to the organic phase from aqueous phase. Bioflotation of quartz using SIP E. coli alone at pH 2.5 gave approximately 60% recovery because at this pH more bacteria adsorb onto the quartz surface and the bacterial surface is hydrophobic. In anionic flotation of quartz using sodium dodecyl sulfate, SIP E. coli cells act as a surface modifier, with an increase in flotation recovery from 28% to 85%. This is because the bacterial cells confer hydrophobic properties to the quartz and the biotreated quartz is positively charged, so a large amount of the collector was adsorbed and the recovery increased.
The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigat... more The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH <4.3 for quartz and at pH 4.5–8.5 for corundum. For hematite, cell adhesion remained low at all pH values. The microbe–mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe–mineral interaction energy (Hamaker constants and acid–base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 × 109 cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite–quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62.
ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian dia... more ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian diatomite is introduced. The optimum conditions for removal of heavy metals using Egyptian diatomite ore were studied as primary step for treatment of hazardous materials in water and wastewater. Metal removal as well as phenol was investigated using synthetic solutions at initial concentrations of 50 mg/L of individual metals (Cd, Cu, Pb, Zn and Ni) and 10 mg/L for phenol at constant temperature (25±0.1 °C) and (pH 5.5±0.2). The removal efficiency was determined at different contact time, different pH and different diatomite doses in order to continue with isothermal models as next step. The optimum contact time was varied between metals and phenols. Moreover, it was varied between the studied metals since, contact time for uptake of Cd and Zn was 15 min, for Cu 30 min. and 60 min for Ni and Pb. On the other hand, optimum contact time for phenol removal was more than 60 minutes. The optimum dose for removal of all metals recorded to be 0.9 g. Locally Egyptian diatomite was efficient in heavy metal as well as phenol removal at optimum conditions. According to the optimum conditions study, the selectivity sequence can be given as Pb2+ &gt; Cu2+ &gt; Cd2+ &gt; Zn2+ &gt;Ni2+. The combination between phenol and metals as well as the competition between them is understudy. The aim of the understudied investigations is increasing the efficiency of diatomite by further modification as well as study of adsorption and desorption behaviors with respect to the studied metals, phenols and some other recalcitrant hazardous organic compound
ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian dia... more ABSTRACT In this study, low cost technique for water treatment from natural abundant Egyptian diatomite is introduced. The optimum conditions for removal of heavy metals using Egyptian diatomite ore were studied as primary step for treatment of hazardous materials in water and wastewater. Metal removal as well as phenol was investigated using synthetic solutions at initial concentrations of 50 mg/L of individual metals (Cd, Cu, Pb, Zn and Ni) and 10 mg/L for phenol at constant temperature (25±0.1 °C) and (pH 5.5±0.2). The removal efficiency was determined at different contact time, different pH and different diatomite doses in order to continue with isothermal models as next step. The optimum contact time was varied between metals and phenols. Moreover, it was varied between the studied metals since, contact time for uptake of Cd and Zn was 15 min, for Cu 30 min. and 60 min for Ni and Pb. On the other hand, optimum contact time for phenol removal was more than 60 minutes. The optimum dose for removal of all metals recorded to be 0.9 g. Locally Egyptian diatomite was efficient in heavy metal as well as phenol removal at optimum conditions. According to the optimum conditions study, the selectivity sequence can be given as Pb2+ &gt; Cu2+ &gt; Cd2+ &gt; Zn2+ &gt;Ni2+. The combination between phenol and metals as well as the competition between them is understudy. The aim of the understudied investigations is increasing the efficiency of diatomite by further modification as well as study of adsorption and desorption behaviors with respect to the studied metals, phenols and some other recalcitrant hazardous organic compound
ABSTRACT Hydrophilic property of Ferroplasma acidiphilum strain was investigated through direct c... more ABSTRACT Hydrophilic property of Ferroplasma acidiphilum strain was investigated through direct contact angle measurements, interaction with hydrocarbons and with the determination of its surface energy components. The contact angles of three different liquids drops (water, chloroform, and 1-bromonaphthalene) positioned on the bacterial lawn were measured. Hamaker constant, electron donor and electron acceptor parameters were calculated. The results of contact angles and those of the interaction with organic solvents showed that the microbe has hydrophilic property. The value of interaction energy, ΔGbwb, between two microbial cells (b) immersed in water (w) was found to be +29.53 mJ/m2 confirming the hydrophilic nature of the microbial cells. The floatability of pyrite under xanthate conditions with and without the microbial cells was examined. The results showed that, when the mineral sample was treated with the microbial cells, the cells rendered their own hydrophilic nature to the mineral surface and the floatability of the mineral decreased dramatically over all pH regions
ABSTRACT Recycled waste glass (RWG), from municipal solid wastes (MSW) sorting operations, may be... more ABSTRACT Recycled waste glass (RWG), from municipal solid wastes (MSW) sorting operations, may be used as a sorbent for cadmium, copper and lead ions removal from industrial wastewaters. To the purpose, the ability of RWG to adsorb Cd2+, Cu2+ and Pb2+ from aqueous solutions has been studied at different operating conditions: contact time, adsorbent amount and metal ion concentration. Batch adsorption kinetic experiments revealed that the sorption of Cd2+, Cu2+ and Pb2+ on RWG was very fast and the equilibrium was practically reached after only 60 min at constant temperature and pH (5.6 ± 0.1). It was found that the adsorption mechanisms follow pseudo-second-order kinetics. The adsorption isotherm studies indicate that the adsorption of Cd2+, Cu2+ onto RWG follows Langmuir isotherms, while Pb2+ can follow Langmuir and Freundlich models. The maximum adsorption capacity (q max) for Cd2+, Cu2+ and Pb2+ were 6.29, 6.68 and 11.68 mg/g, respectively. From Dubinin–Kaganer–Radushkevich (DKR), the free energy E-value for Cd2+, Cu2+ and Pb2+ is 14.067, 18.467 and 19.724 kJ/mol, respectively. The positive values of E indicate that the sorption process is endothermic and the energy values for the studied metals sorption on RWG indicate that the sorption process is physisorption.
ABSTRACT Application of microorganisms as surface modifiers in flocculation has generated a great... more ABSTRACT Application of microorganisms as surface modifiers in flocculation has generated a great deal of interest in recent times. The surface properties such as zeta-potential and hydrophobicity of minerals and microorganisms play a major role in determining the adsorption of microorganisms onto the minerals and hence the efficiency of flocculation. The utility of microorganisms, including Escherichia coli (wild-type and genetically modified strain Sip), Arthrobacter nicotianae, Bacillus licheniformis, and Pseudomonas maltophilia, has been evaluated by measuring their zeta-potentials and carrying out adsorption and flocculation experiments. Of the tested microorganisms, adsorption of E. coli strain Sip significantly modified the quartz surface. The zeta-potential of the quartz became highly positive at acidic pH, and its IEP (isoelectric point) was shifted from pH
Journal of colloid and interface science, Jan 1, 2010
The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated expe... more The adhesion behavior of Ferroplasma acidiphilum archaeon to pyrite mineral was investigated experimentally and theoretically. F. acidiphilum showed high affinity to adhere to pyrite surface at acidic regions, however low affinity was observed at neutral and alkaline regions. The microbe–mineral adhesion was assessed by the extended DLVO theory. Hamaker constants, electron donors, electron acceptors and surface charges for the microbe and the mineral were experimentally determined. The extended DLVO theory was used to explain the adhesion results. Significant changes to the pyrite surface properties after being treated with the microbial cells were observed. Pyrite lost its hydrophobic nature and became hydrophilic, the contact angle of untreated pyrite was 61° and this decreased to 36° after the treatment. As a consequence, the flotation experiment results showed that F. acidiphilum strain could act as a good depressant for pyrite in xanthat flotation; where in absence of F. acidiphilum cells, over 95% of pyrite can be recovered as a float. However, when the mineral was pretreated with F. acidiphilum cells, less than 20% can be recovered as a float.Effect of cell shape on mineral–microbe interaction energy and adhesion behavior (at pH 10.5).
Zeta potential measurements of silica-induced protein (SIP) Escherichia coli and quartz showed th... more Zeta potential measurements of silica-induced protein (SIP) Escherichia coli and quartz showed that the former are positively charged under acidic condition and negatively charged under neutral and alkaline conditions, with an isoelectric point (IEP) at pH 4.5, while the quartz was always negatively charged. Adsorption experiments with bacteria cells on quartz were conducted under different conditions. The results show that at pH values lower than the IEP of the cells, more cells were adsorbed due to electrostatic forces. However, at pH > 4.5, the amount of adsorbed cells decreased as a result of electrostatic repulsion forces. Zeta potentials of quartz showed that at pH 2.5 a significant change in the surface chemistry of quartz occurred after bacterial treatment. The degree of this change was related to the initial SIP E. coli concentration; at 5 × 107 cells/ml the average zeta potential of biotreated quartz shifted from –30 mV to 0 mV and at higher concentrations the zeta potential shifted to the positive direction and reached a similar value to that of the bacterial cells. SIP E. coli showed hydrophobic properties at pH lower than the IEP, with approximately 60% of the cells moving to the organic phase from aqueous phase. Bioflotation of quartz using SIP E. coli alone at pH 2.5 gave approximately 60% recovery because at this pH more bacteria adsorb onto the quartz surface and the bacterial surface is hydrophobic. In anionic flotation of quartz using sodium dodecyl sulfate, SIP E. coli cells act as a surface modifier, with an increase in flotation recovery from 28% to 85%. This is because the bacterial cells confer hydrophobic properties to the quartz and the biotreated quartz is positively charged, so a large amount of the collector was adsorbed and the recovery increased.
The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigat... more The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH <4.3 for quartz and at pH 4.5–8.5 for corundum. For hematite, cell adhesion remained low at all pH values. The microbe–mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe–mineral interaction energy (Hamaker constants and acid–base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 × 109 cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite–quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62.
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